1. Field of the Invention
This invention relates to an improved electrical outlet box connector and combination outlet box and connector.
2. Description of the Prior Art
This invention is an improvement upon the outlet box connector disclosed in my prior U.S. pat. No. 3,728,470 issued Apr. 17, 1973 for an ELECTRICAL OUTLET BOX WITH CABLE CONNECTORS. The outlet box disclosed in my aforesaid patent is provided with knock-out plugs which, when removed, result in formation of irregularly shaped openings for reception of cable connectors. Each knock-out plug is shaped so that when it is removed it leaves a substantially circular yet irregular opening, the edge of the opening having a pair of diametrically opposed arcuate recesses. The connector disclosed in my aforesaid patent which is adapted to be inserted in one of the outlet box openings and rotated approximately 90.degree. to lock the connector in the opening comprises a tubular body an inner portion adapted to be inserted in the box opening and an outer portion adapted to receive the end of an electrical cable. An annular shoulder is provided on the connector for abutting the outer surface of the box wall surrounding an opening therein and a pair of arcuate lugs is provided at diametrically opposite sides of the connector for passage through recesses in the edge of the box opening when the connector is inserted in the opening. Raised arcuate portions are provided between the annular shoulder and the arcuate lugs which exceed the diameter of the opening the box wall and become wedged against the edge of the opening when the connector is rotated in the opening. The walls of the outlet box which have the knock-out plugs are of relative hard metal while the connector is made of a softer metal so that when the connector is rotated in the opening, hard metal edges provided in the opening bite into the soft metal raised portions. Experience with the outlet boxes and connectors disclosed in my aforesaid patent has shown that sometimes an excessive turning force is applied when rotating the connector in the box opening which will strip the upper layer of metal from the raised portion and which will defeat the wedging action of the raised portions allowing the connector to turn freely in the opening.
The present invention includes the features described above of the outlet box and connector disclosed in my aforesaid patent but is an improvement thereover in that diametrically opposed flat raised portions are provided adjacent to the arcuate portions which provide areas of increasing diameter as the connector is turned in order to provide a positive stop at the end of the raised arcuate portions to limit further rotation of the connector should an excessive torque be applied in rotating the connector which would tend to strip off the upper surfaces of the raised arcuate portions.
Another feature of the present invention which is an improvement over the connector of my prior patent is an annular bushing integrally mounted within the connector and spaced from the inside surface thereof to serve as a spacer between the out metal sheath of a metal sheathed cable and the cable insulation at the end of the cable inserted in the outer portion of the connector. The integral bushing replaces separate bushings which many electrical codes require. The bushing distinguishes from the cable end stop provided in the connector of my prior patent in that it fits inside of the cable sheath whereas the end stop of the connector of my prior patent does not.
Still another feature of the present invention is the provision of inwardly depressed helical tongues integral with the connector for engaging grooves in the cable sheath and for locking the cable in the connector. Each of the tongues is formed by making axially spaced parallel helical cuts through the wall of the connector forming side edges of the tongue and by making a transverse cut across corresponding ends of the helical cuts forming a free end of the tongue. The tongue is bent inwardly about a hinge line across the corresponding ends of the helical cuts opposite said free end. The tongues are spaced in a helical pattern about the connector beginning at the outer end of the outer portion thereof spiralling inwardly in the manner of internal threads. A sheathed metal cable having helical grooves formed on its outer surface may be threaded into the outer portion of the connector until the inner end of the cable is forced against the inner bushing. The tongues prevent the cable from being pulled out of the connector by an axial force and prevent the cable from being screwed reversely by the action of the sharp edges at the free end of the tongue digging into the cable sheath. Helical internal threads in a connector are not new, however the helically arranged inwardly depressed tongues of the present invention are believed to an improvement over the prior art.